The present invention relates, in general, to a switching device.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Switching devices of a type involved here disconnect a line network from the power grid in the event of excess currents in the line network lasting for a presettable time, in order to prevent further supply of electric current. There are also switching devices which disconnect a line network from the power grid in the event of a short-circuit in the line network to prevent further supply of electric current. Such switching devices have therefore a so-called overcurrent trigger device and/or a short-circuit trigger device, which upon actuation trigger a mechanical disconnect device which disconnects the switching contacts of the switching device and prevents further current flow. The overcurrent trigger device and/or a short-circuit trigger device typically operate mechanically on a mechanical trigger of the disconnect device.
It is known that the overcurrent trigger device and/or the short-circuit trigger device does not operate directly on the disconnect device and therefore does not trigger the disconnect device by direct mechanical actuation without a linkage member, because the overcurrent trigger device and/or the short-circuit trigger device are frequently arranged as an assembly in the switching device and remote from the disconnect device. Switching devices constructed in this manner therefore have a mechanical linkage member between the overcurrent trigger device and/or short-circuit trigger device and the disconnect device. Disadvantageously, the mechanical force applied by the overcurrent trigger device and/or the short-circuit trigger device on the disconnect device can damage the overcurrent trigger device, the short-circuit trigger device, the linkage member and or the disconnect device. A damaged switching device may not be triggered during the next event when it needs to be triggered. Because such damage is in many cases not externally apparent, damaged switching devices are not replaced and therefore represent a serious danger to people and facilities.
It would therefore be desirable and advantageous to provide an improved switching device which obviates prior art shortcomings and which is reliable and safe in operation.